Coating material that can be cured thermally or by actinic radiation, and its use

ABSTRACT

The invention relates to a coating material that can be cured thermally or by actinic radiation and that contains at least one component (a1) with at least two functional groups (a11) which serve for cross-linking, by actinic radiation, and at least one functional group (a12) that can enter into thermal cross-linking reactions with the hydroxyl and/or thiol groups (a21) in component (a2), at least one branched cyclic and/or acyclic C 9 -C 16  alkane (a2)) that is functionalized with at least two hydroxyl or thiol groups (a21) or with at least one hydroxyl and at least one thiol group, and optionally at least one photo initiator (a3), at least one initiator of the thermal cross-linking reaction (a4), at least one reactive diluent that is cured by actinic radiation and/or thermafly, at least one lacquer additive (a6), at least one thermally curable component (a7) and/or at least one organic solvent (a8). The inventive coating material is used to produce transparent lacquers and multi-layer chromophor and/or effect lacquers.

This application is a National Phase Application of Patent ApplicationPCT/EP00/04807 filed on May 26, 2000.

The present invention relates to a novel coating material curablethermally and with actinic radiation. The present invention also relatesto the use of the novel coating material for producing novel clearcoatsand multicoat color and/or effect coating systems for automotive OEMfinishing and refinish, industrial coating, including coil coating andcontainer coating, the coating of plastics, and furniture coating.

Automobile bodies, plastic parts for automobiles or domestic appliancesand industrial components are nowadays protected by a clearcoat. Theclearcoat may be the only coating film used, or else may form theuppermost coat of a multicoat topcoat system.

Automobile bodies in particular are provided extensively with amulticoat topcoat system. Clearcoats are frequently applied as the finalcoat. Materials suitable for this purpose are the customary and knownone-component (1K), two-component (2K), multicomponent (3K, 4K), powderclearcoat or powder slurry clearcoat materials, or UV-curable clearcoatmaterials.

One-component (1K), two-component (2K) or multicomponent (3K, 4K)clearcoat materials are described, for example, in the patents U.S. Pat.No. 5,474,811, U.S. Pat. No. 5,356,669, U.S. Pat. No. 5,605,965, WO94/10211, WO 94/10212, WO 94/10213, EP 0 594 068 A1, EP 0 594 071 A1, EP0 594 142 A1, EP 0 604 992 A1, WO 94/22969, EP 0 596 460 A1, and WO92/22615.

Powder clearcoat materials are known, for example, from the Germanpatent DE 42 22 294 A1 or from the BASF Lacke+Farben AG productinformation bulletin “Pulverlacke” [Powder coating materials], 1990.

A powder coating material which is curable thermally and with actinicradiation is known from the European patent EP 0 844 286 A1. Itcomprises an unsaturated binder and a second resin, copolymerizable withthe first, and also a photoinitiator and a thermal initiator, andaccordingly is curable thermally and with actinic radiation. However,this dual-cure powder coating material is used as a pigmented topcoatmaterial, which is cured superficially with UV light and thermally inthe regions close to the substrate. The patent does not reveal whetherthis known powder coating material is also suitable for producingclearcoats, especially in multicoat systems.

Powder slurry coating materials comprise powder coating materials in theform of aqueous dispersions. Slurries of this kind are described, forexample, in the U.S. patent U.S. Pat. No. 4,268,542 and in the Germanpatent applications DE 195 18 392.4 A1 and DE 196 13 547 A1, and in theGerman patent application DE 198 14 471.7 A1, which was unpublished atthe priority date of the present specification.

UV-curable clearcoat materials are disclosed, for example, by thepatents EP 0 540 884 A1, EP 0 568 967 A1 or U.S. Pat. No. 4,675,234 A1.

Each of these clearcoat materials has specific strengths and weaknesses.Using these clearcoat materials, multicoat systems are obtained whichsatisfy the optical requirements. However, the scratch-resistantone-component (1K) clearcoat materials are sometimes not sufficientlyweather-resistant, whereas the weather-resistant two-component (2K) ormulticomponent (3K, 4K) clearcoat materials are often not sufficientlyscratch-resistant. Certain one-component (1K) clearcoat materials areindeed scratch-resistant and weather-stable but, in combination withfrequently employed waterborne basecoat materials, exhibit surfacedefects such as shrinkage (wrinkling).

Powder clearcoat materials, powder slurry clearcoat materials, andUV-curabled clearcoat materials, on the other hand, exhibit a notentirely satisfactory intercoat adhesion, without offering a completesolution to the problems of scratch resistance or etch resistance. Inparticular, the severe polymerization shrinkage of the UV-curableclearcoat materials gives them a particular tendency towardsdelamination.

EP 0 568 967 A1 discloses a process for producing multicoat systems inwhich a thermally curable clearcoat film is applied by the wet-on-wettechnique to a pigmented basecoat film, after which the two films areheat-cured together. Atop of the cured clearcoat there is subsequentlyapplied at least one further clearcoat film, based on coating materialscurable with actinic radiation, and curing is carried out with actinicradiation, or thermally and with actinic radiation. This process givesclearcoats of high chemical resistance and optical quality. However, thescratch resistance is not satisfactory.

Furthermore, EP 0 568 967 A1 discloses a process in which a coatingmaterial curable with actinic radiation is applied to the pigmentedbasecoat film and cured. Subsequently, a further coat of the samecoating material is applied and is cured with actinic radiation.Although this results in a highly glossy surface without perceptibletexture, the clearcoat in question yellows. Additionally, the scratchresistance still leaves something to be desired.

It is an object of the present invention to provide a novel coatingmaterial which no longer has the disadvantages of the prior art butwhich instead provides, simply, novel clearcoats and color and/or effectcoating systems which exhibit no elimination of constituents on bakingand which are scratch-resistant, stable to weather, free from yellowing,hard, flexible, and free from surface defects, which exhibit a highlevel of adhesion on all substrates, and which may be produced in thehigh coat thickness needed for an outstanding overall appearance.

The invention accordingly relates to a novel coating material curablethermally and with actinic radiation, comprising

(a1) at least one constituent containing

(a11) at least two functional groups which serve for crosslinking withactinic radiation, and

(a12) at least one functional group which is able to undergo thermalcrosslinking reactions with the hydroxyl and/or thiol groups (a21) inthe constituent (a2), and

(a2) at least one branched, cyclic and/or acyclic C₉-C₁₆ alkanefunctionalized with at least two hydroxyl or thiol groups or with atleast one hydroxyl and at least one thiol group (a21).

In the text below, the novel coating material curable thermally and withactinic radiation is referred to as the “coating material of theinvention”.

In the text below, the branched, cyclic and/or acyclic C₉-C₁₆ alkanes(a2) for use in accordance with the invention that are functionalizedwith at least two hydroxyl or thiol groups or with at least one hydroxyland at least one thiol group are referred to for short as“functionalized alkanes (a2)”.

The invention further provides the novel clearcoats and multicoat colorand/or effect coating systems which can be produced with the aid of thecoating material of the invention.

In the text below, the novel clearcoats and multicoat color and/oreffect coating systems are referred to as “clearcoat of the invention”and “multicoat systems of the invention”, and the correspondingprocesses for producing them are referred to as “coating processes ofthe invention”.

In the context of the present invention, the term “thermal curing”denotes the heat-initiated curing of a film of a coating material, inthe context of which normally a separate crosslinking agent is employed.This is customarily referred to by those in the art as externalcrosslinking. Where the crosslinking agents are built into the binders,the term self-crosslinking is used. In accordance with the invention,external crosslinking is of advantage and is therefore employed withpreference.

In the context of the present invention, actinic radiation meanselectron beams or, preferably, UV radiation. Curing by UV radiation isnormally initiated by free-radical or cationic photoinitiators and interms of its mechanism is a free-radical or cationicphotopolymerization.

Where thermal curing and curing with actinic light are employed togetherfor a coating material, the term “dual cure” is also used.

In the light of the prior art it was surprising and unforeseeable forthe skilled worker that the object on which the invention is based mightbe achieved with the aid of the coating material of the invention, thecoating process of the invention, and the clearcoat and multicoatsystems of the invention.

A particular surprise is that use of the coating material of theinvention results in clearcoat and multicoat systems of the inventionwhich exhibit no elimination of constituents on baking and which notonly are scratch-resistant, stable to weathering, free from yellowing,hard, flexible and free from surface defects, exhibit a high level ofadhesion on all substrates and may be produced in the high coatthickness necessary for an outstanding overall visual impression, butalso have extremely high reflow.

The basic material of the invention comprises at least one constituent(a1) containing at least two functional groups (a11) which serve forcrosslinking with actinic radiation.

Examples of suitable functional groups (a11) are epoxide groups orolefinically unsaturated double bonds, as are present in vinyl, allyl,cinnamoyl, methacrylic or acrylic groups, especially methacrylic oracrylic groups. As is known, the epoxide groups are used for cationicphotopolymerization, whereas the olefinically unsaturated double bondsare primarily suitable for free-radical photopolymerization. Inaccordance with the invention, the constituent (a1) may contain epoxidegroups and olefinic double bonds, so that it may be subjected tocrosslinking with actinic radiation in accordance with both mechanisms.It is, however, of advantage to use exclusively olefinically unsaturateddouble bonds, of the type specified, as functional group (a11).

The constituent (a1) for use in accordance with the invention furthercomprises at least one, preferably at least two functional groups (a12)which are able to undergo thermal crosslinking reactions with thehydroxyl and/or thiol groups (a21) of the constituent (a2) describedbelow.

Examples of suitable functional groups (a12) are evident from thefollowing overview.

Overview: Examples of complementary functional groups (a12) and (a22) in

In the overview the radicals R denote aliphatic, cycloaliphatic,aromatic, aliphatic-cycloaliphatic, aliphatic-aromatic orcycloaliphatic-aromatic organic groups which if desired are substitutedand/or contain heteroatoms such as oxygen, nitrogen and/or sulfur.

The selection of the groups (a21) is guided on the one hand by theconsideration that they should not enter into any unwanted reactionsinitiated by actinic radiation and should not disrupt or inhibit curingwith actinic radiation, and secondly by the temperature range withinwhich thermal curing is to take place. In this context it is ofadvantage in accordance with the invention, especially with regard toheat-sensitive substrates such as plastics, to choose a temperaturerange which does not exceed 100° C., in particular 80° C. In the lightof these boundary conditions, isocyanate groups (a12) have provenadvantageous, and so are employed with preference in accordance with theinvention.

Accordingly, the particularly advantageous constituent (a1) is anoligomeric or polymeric compound curable thermally or with actinicradiation which comprises at least one, preferably at least two and inparticular at least three isocyanate groups (a12) and at least two andin particular at least three (meth)acrylic groups (a11).

In the context of the present invention, an oligomeric compound is acompound containing in general on average from 2 to 15 repeating basicstructures or monomer units. A polymeric compound, in contrast, is acompound which generally contains on average at least 10 repeating basicstructures or monomer units. Compounds of this kind are also referred toby those in the art as binders or resins.

In contradistinction thereto, a low molecular mass compound in thecontext of the present invention is a compound which derivessubstantially only from one basic structure or one monomer unit.Compounds of this kind are also referred to generally by those in theart as reactive diluents.

The polymers or oligomers used as constituent (a1) normally have anumber-average molecular weight of from 500 to 50 000, preferably from1000 to 5000. They preferably have a double bond equivalent weight offrom 400 to 2000, with particular preference from 500 to 900.Furthermore, they have a viscosity at 23° C. of preferably from 250 to11 000 mPas. They are employed preferably in an amount of from 5 to 90%by weight, with particular preference from, 10 to 80% by weight, and inparticular from 15 to 70% by weight, based in each case on the overallamount of the coating material.

Examples of suitable constituents (a1) come from the oligomer and/orpolymer classes of the linear or branched, especially the branched,(meth) acryl-functional (meth)acrylic copolymers, polyether acrylates,polyester acrylates, unsaturated polyesters, epoxy acrylates, urethaneacrylates, amino acrylates, melamine acrylates, silicone acrylates, andthe corresponding methacrylates. It is preferred to use binders (a1)which are free from aromatic structural units. Preference is thereforegiven to using urethane (meth)acrylates and/or polyester(meth)acrylates, with particular preference to urethane (meth)acrylates,with very particular preference aliphatic urethane (meth)acrylates, andespecially urethane acrylates.

The urethane (meth)acrylates (a1) are obtained by reacting adiisocyanate and/or polyisocyanate, in particular a polyisocyanate, witha chain extender from the group of the diols/polyols and/ordiamines/polyamines and/or dithiols/polythiols and/or alkanolamines andthen reacting some of the free isocyanate groups with at least onehydroxyalkyl (meth)acrylate, especially a hydroxyalkyl acrylate. Ifdesired, hydroxyalkyl esters of other ethylenically unsaturatedcarboxylic acids such as ethacrylic acid or itaconic acid may be used aswell.

The amounts of chain extender, diisocyanate and/or polyisocyanate, andhydroxyalkyl ester in this case are preferably chosen so that

1.) the ratio of equivalents of the NCO groups to the reactive groups ofthe chain extender (hydroxyl, amino and/or thiol groups) is between 20:1and 2:1, preferably between 15:1 and 5:1, and

2.) the OH groups of the hydroxyalkyl esters of the ethylenicallyunsaturated carboxylic acids are substoichiometric with regard to theremaining free isocyanate groups of the prepolymer formed fromisocyanate and chain extender.

It is also possible to prepare the urethane (meth)acrylate (a1) by firstreacting some of the isocyanate groups of a polyisocyanate with at leastone hydroxyalkyl ester and then reacting some of the remainingisocyanate groups with a chain extender. In this case too the amounts ofchain extender, isocyanate and hydroxyalkyl ester are chosen so that theratio of equivalents of NCO groups to the reactive groups of the chainextender is between 20:1 and 2:1, preferably between 15:1 and 5:1, andthe ratio of equivalents of the remaining NCO groups to the OH groups ofthe hydroxyalkyl ester is more than 1.

All of the forms lying between these two processes are of course alsopossible. Overall, it should be ensured that the ratio of isocyanategroups to isocyanate-reactive groups is sufficiently high that theresultant urethane (meth)acrylate (a1) possesses the desired number ofisocyanate groups (a12).

In accordance with the invention the urethane (meth)acrylate (a1)contains on average at least one, preferably at least two, isocyanategroup(s) (a12). Particular advantages result if there are on averagemore than two, with very particular preference more than three,isocyanate groups (a12). The number of isocyanate groups (a12) per[lacuna] need not exceed six on average in order to obtain theadvantages of the invention. However, in specific cases an average ofeven more than six isocyanate groups (a12) per urethane (meth)acrylate(a1) is found advantageous.

Particular advantages result if the constituent (a1), especially theurethane (meth)acrylate (a1), has an isocyanate group (a12) content offrom 7 to 20% by weight, with particular preference from 8 to 18% byweight, and in particular from 9 to 16% by weight, based in each case onthe constituent (a1).

Examples of suitable diisocyanates and/or polyisocyanates are thosedescribed below in connection with the crosslinking agent (a7). Forpurposes of the preparation of the constituent (a1), especially theurethane (meth)acrylate (a1), the polyisocyanurates described at thatpoint, containing isocyanurate groups, are of particular advantage andare therefore used with particular preference.

The coating material of the invention further comprises thefunctionalized alkanes (a2).

The functionalized alkanes (a2) are derived from branched, cyclic oracyclic alkanes having from 9 to 16 carbon atoms, which in each caseform the parent structure.

Examples of suitable alkanes of this kind having 9 carbon atoms are2-methyloctane, 4-methyloctane, 2,3-dimethylheptane,3,4-dimethylheptane, 2,6-dimethylheptane, 3,5-dimethylheptane,2-methyl-4-ethylhexane, and isopropylcyclohexane.

Examples of suitable alkanes of this kind having 10 carbon atoms are4-ethyloctane, 2,3,4,5-tetramethylhexane, 2,3-diethylhexane, and1-methyl-2-n-propylcyclohexane.

Examples of suitable alkanes of this kind having 11 carbon atoms are2,4,5,6-tetramethylheptane and 3-methyl-6-ethyloctane.

Examples of suitable alkanes of this kind having 12 carbon atoms are4-methyl-7-ethylnonane, 4,5-diethyloctane, 1′-ethylbutylcyclohexane,3,5-diethyloctane, and 2,4-diethyloctane.

Examples of suitable alkanes of this kind having 13 carbon atoms are3,4-dimiethyl-5-ethylnonane and 4,6-dimethyl-5-ethylnonane.

An example of a suitable alkane of this kind having 14 carbon atoms is3,4-dimethyl-7-ethyldecane.

Examples of suitable alkanes of this kind having 15 carbon atoms are3,6-diethylundecane and 3,6-dimethyl-9-ethylundecane.

Examples of suitable alkanes of this kind having 16 carbon atoms are3,7-diethyldodecane and 4-ethyl-6-isopropylundecane.

Of these parent structures, the alkanes having from 10 to 14 and inparticular 12 carbon atoms are particularly advantageous and aretherefore used with preference. Of these, the octane derivatives in turnare especially advantageous.

For the present invention it is advantageous if the functionalizedalkanes (a2) which derive from these branched, cyclic or acyclic alkanesas parent structures are liquid at room temperature. Accordingly, it ispossible to use either individual liquid functionalized alkanes (a2) orliquid mixtures of these compounds. This is especially the case whenusing functionalized alkanes (a2) which, owing to their high number ofcarbon atoms in the alkane parent structure, are solid as individualcompounds. The skilled worker will therefore be able to select thecorresponding functionalized alkanes (a2) in a simple manner.

For the invention it is also advantageous for the functionalized alkanes(a2) to have a boiling point of more than 200, preferably 220, and inparticular 240° C. Moreover, they should have a low evaporation rate.

For the coating materials of the invention it is of advantage if thefunctionalized alkanes (a2) are acyclic.

The functionalized alkanes (a2) have primary and/or secondary hydroxyland/or thiol groups. For the coating materials of the invention it is ofadvantage if primary and secondary groups of this kind are present inone compound.

Accordingly, the functionalized alkanes (a2) comprise polyols,polythiols or polyol-polythiols (a2), but especially polyols (a2). Thesecompounds may be used individually, or together as mixtures. Particularadvantage arise if the polyols (a2) are diols and/or triols, butespecially diols. They are therefore used with very particularpreference.

Especially advantageous coating materials of the invention are obtainedif the polyols (a2) are positionally isomeric dialkyloctanediols,especially diethyloctanediols. Outstanding results are obtained with2,4-diethyl-1,5-octanediol.

The above-described functionalized alkanes (a2) are compounds known perse and may be prepared by means of customary and known synthesis methodsof organic chemistry such as base-catalyzed aldol condensation, or theyare obtained as byproducts of chemical industrial syntheses such as thepreparation of 2-ethylhexanol.

The functionalized alkanes (a2) are generally present in the coatingmaterials of the invention in an amount of from 5 to 60% by weight,based on the overall amount of the coating material in question.Although they may be present therein in greater amounts, the rangeindicated is an advantageous range within which the advantages of theinvention are achieved reliably and securely. Within this range, thatfrom 10 to 50% by weight is of particular advantage, since the coatingmaterials of the invention which contain this amount of functionalizedalkanes (a2) have a particularly advantageous profile of properties.Very particular advantages result, however, from the use of from 15 to40% by weight of functionalized alkanes (a2).

In the coating material of the invention the ratio of isocyanate groups(a12) to the isocyanate-reactive groups (a21) may vary widely. It isguided in particular by the technical effects which have to be achievedwith regard to the clearcoat and multicoat system of the invention. Inaccordance with the invention it is of advantage if the ratio(a12)/(a21) is between 2:1 and 1:2, with particular preference between1.5:1 and 1:1.5.

The coating material for use in accordance with the invention maycomprise at least one photoinitiator (a3). If the coating material orclearcoat film is to be crosslinked with UV radiation, the use of aphotoinitiator (a3) is generally necessary. Where such initiators areused, they are present in the coating material in fractions ofpreferably from 0.1 to 10% by weight, [lacuna] from 1 to 8% by weight,and in particular from 2 to 6% by weight, based in each case on theoverall amount of the coating material.

Examples of suitable photoinitiators (a3) are those of the Norrish IItype, whose mechanism of action is based on an intramolecular variant ofthe hydrogen abstraction reactions as occur diversely in photochemicalreactions (by way of example, reference may be made here to Römpp ChemieLexikon, 9th expanded and revised edition, Georg Thieme Verlag,Stuttgart, Vol. 4, 1991) or cationic photoinitiators (by way of example,reference may be made here to Römpp Lexikon Lacke und Druckfarben, GeorgThieme Verlag Stuttgart, 1998, pages 444 to 446), especiallybenzophenones, benzoins or benzoin ethers, or phosphine oxides. It isalso possible to use, for example, the products available commerciallyunder the names Irgacure® 184, Irgacure® 1800 and Irgacure® 500 fromCiba Geigy, Grenocure® MBF from Rahn, and Lucirin® TPO from BASF AG.

Besides the photoinitiators (a3), customary sensitizers (a3) such asanthracene may be used in effective amounts.

Furthermore, the coating material may comprise at least one thermalcrosslinking initiator (a4). At from 80 to 120° C., these initiatorsform radicals which start the crosslinking reaction. Examples ofthermolabile free-radical initiators are organic peroxides, organic azocompounds or C—C-cleaving initiators such as dialkyl peroxides,peroxocarboxylic acids, peroxodicarbonates, peroxide esters,hydroperoxides, ketone peroxides, azo dinitriles or benzpinacol silylethers. C—C-cleaving initiators are particularly preferred, since theirthermal cleavage does not produce any gaseous decomposition productswhich might lead to defects in the coating film. Where used, theiramounts are generally from 0.1 to 10% by weight, preferably from 0.5 to8% by weight, and in particular from 1 to 5% by weight, based in eachcase on the overall amount of the coating material.

Moreover, the coating material may comprise at least one reactivediluent (a5) curable thermally and/or with actinic radiation.

Examples of suitable thermally crosslinkable reactive diluents (a5) areoligomeric polyols which are obtainable from oligomeric intermediates,themselves obtained by metathesis reactions of acyclic monoolefins andcyclic monoolefins, by hydroformylation and subsequent hydrogenation;examples of suitable cyclic monoolefins are cyclobutene, cyclopentene,cyclohexene, cyclooctene, cycloheptene, norbonene or 7-oxanorbonene;examples of suitable acyclic monoolefins are contained in hydrocarbonmixtures obtained in petroleum processing by cracking (C₅ cut); examplesof suitable oligomeric polyols for use in accordance with the inventionhave a hydroxyl number (OHN) of from 200 to 450, a number-averagemolecular weight Mn of from 400 to 1000, and a mass-average molecularweight Mw of from 600 to 1100.

Further examples of suitable thermally crosslinkable reactive, diluents(a5) are hyperbranched compounds containing a tetrafunctional centralgroup, derived from ditrimethylolpropane, diglycerol,ditrimethlylolethane, pentaerythritol, tetrakis (2-hydroxyethyl)methane,tetrakis(3-hydroxypropyl)methane or 2,2-bishydroxymethyl-1,4-butanediol(homopentaerythritol). The preparation of these reactive diluents maytake place in accordance with the customary and known methods ofpreparing hyperbranched and dendrimeric compounds. Suitable synthesismethods are described, for example, in the patents WO 93/17060 or WO96/12754 or in the book by G. R. Newkome, C. N. Moorefield and F.Vögtle, Dendritic Molecules, Concepts, Syntheses, Perspectives, VCH,Weinheim, New York, 1996.

Further examples of suitable reactive diluents (a5) arepolycarbonatediols, polyesterpolyols, poly(meth)acrylatediols orhydroxyl-containing polyaddition products.

Examples of suitable reactive solvents which may be used as reactivediluents (a5) are butyl glycol, 2-methoxypropanol, n-butanol,methoxybutanol, n-propanol, ethylene glycol monomethyl ether, ethyleneglycol monoethyl ether, ethylene glycol monobutyl ether, diethyleneglycol monomethyl ether, diethylene glycol monoethyl ether, diethyleneglycol diethyl ether, diethylene glycol monobutyl ether,trimethylolpropane, ethyl 2-hydroxypropionate or3-methyl-3-methoxybutanol and also derivatives based on propyleneglycol, e.g., ethoxyethyl propionate, isopropoxypropanol ormethoxypropyl acetate.

As reactive diluents (a5) which may be crosslinked with actinicradiation, use is made, for example, of (meth)acrylic acid and estersthereof, maleic acid and its esters, including monoesters, vinylacetate, vinyl ethers, vinylureas, and the like. Examples that may bementioned include alkylene glycol di(meth)acrylate, polyethylene glycoldi(meth)acrylate, 1,3-butandiol di(meth)acrylate, vinyl(meth)acrylate,allyl(meth)acrylate, glycerol tri(meth)acrylate, trimethylol-propanetri(meth)acrylate, trimethylolpropane di(meth)acrylate, styrene,vinyltoluene, divinylbenzene, pentaerythritol tri(meth)acrylate,pentaerythritol tetra(meth)acrylate, dipropylene glycoldi(meth)acrylate, hexanediol di(meth)acrylate, ethoxyethoxyethylacrylate, N-vinylpyrrolidone, phenoxyethyl acrylate, dimethylaminoethylacrylate, hydroxyethyl (meth)acrylate, butoxyethyl acrylate,isobornyl(meth)acrylate, dimethylacrylamide and dicyclopentyl acrylate,the long-chain linear diacrylates described in EP 0 250 631 A1 having amolecular weight of from 400 to 4000, preferably from 600 to 2500. Forexample, the two acrylate groups may be separated by a polyoxybutylenestructure. It is also possible to use 1,12-dodecyl diacrylate and thereaction product of 2 moles of acrylic acid with 1 mole of a dimer fattyalcohol having generally 36 carbon atoms. Also suitable are mixtures ofthe aforementioned monomers.

Preferred reactive diluents (a5) used include mono- and/or diacrylates,such as isobornyl acrylate, hexanediol diacrylate, tripropylene glycoldiacrylate, Laromer® 8887 from BASF AG and Actilane® 423 from AkcrosChemicals Ltd., GB. Particular preference is given to using isobornylacrylate, hexanediol diacrylate and tripropylene glycol diacrylate.

Where used, the reactive diluents (a5) are employed in an amount ofpreferably from 2 to 70% by weight, with particular preference from 10to 65% by weight, and in particular from 15 to 50% by weight, based ineach case on the overall amount of the coating material.

The coating material may further comprise at least one customary andknown coatings additive (a6) in effective amounts, i.e., in amounts[lacuna] preferably up to 40% by weight, with particular preference upto 30% by weight, and in particular up to 20% by weight, based in eachcase on the overall amount of the coating material.

Examples of suitable coatings additives (a6) are

UV absorbers;

light stabilizers such as HALS compounds, benzotriazoles oroxalanilides;

free-radical scavengers;

crosslinking catalysts such as dibutyltin dilaurate or lithiumdecanoate;

slip additives;

polymerization inhibitors;

defoamers;

emulsifiers, especially nonionic emulsifiers such as alkoxylatedalkanols and polyols, phenols and alkylphenols or anionic emulsifierssuch as alkali metal salts or ammonium salts of alkanecarboxylic acids,alkanesulfonic acids, and sulfo acids of alkoxylated alkanols andpolyols, phenols and alkylphenols;

wetting agents such as siloxanes, fluorine compounds, carboxylicmonoesters, phosphoric esters, polyacrylic acids and their copolymers,or polyurethanes;

adhesion promoters such as tricyclodecane-dimethanol;

leveling agents;

film formation auxiliaries such as cellulose derivatives;

transparent fillers such as pyrogenic silica or nanoparticles based onsilica; for further details, refer to Römpp Lexikon Lacke undDruckfarben, Georg Thieme Verlag, Stuttgart, 1998, pages 250 to 252;

flame retardants, and/or

flatting agents.

Further examples, of suitable coatings additives (a6) are described inthe textbook [Lackadditive Additives for coatings] by Johan Bieleman,Wiley-VCH, Weinheim, New York, 1998.

Not least, the coating material may comprise minor amounts of at leastone thermally curable constituent (a7). In the context of the presentinvention, minor amounts are amounts which do not adversely affect thedual cure properties of the coating material but instead advantageouslyvary and supplement them. Where used, their fractions in the coatingmaterial should generally not exceed 40% by weight, preferably 35% byweight, and in particular 30% by weight.

Examples of suitable constituents (a7) are the crosslinking agents andbinders known from the thermally curable coating materials.

Examples of suitable binders (a7) are linear and/or branched and/orblock, comb and/or random poly(meth)acrylates or acrylate copolymers,polyesters, alkyds, amino resins, polyurethanes, polylactones,polycarbonates, polyethers, epoxy resin-amine adducts,(meth)acrylatediols, partially saponified polyvinyl esters or polyureas,of which the acrylate copolymers, the polyesters, the polyurethanes, thepolyethers and the epoxy resin-amine adducts are advantageous.

Suitable binders (a7) are sold, for example, under the tradenamesDesmophen® 650, 2089, 1100, 670, 1200 or 2017 by Bayer, under the tradenames Priplas or Pripol® by Uniqema, under the trade names Cempol®polyester or polyacrylate-polyol by CCP, under the trade names Crodapol®0-85 or 0-86 by Croda or under the trade name Formrez® ER417 by Witco.

Examples of suitable crosslinking agents (a7) are blocked diisocyanatesand/or polyisocyanates.

Examples of suitable diisocyanates and/or polyisocyanates for thepreparation of the blocked derivatives (a7) are organic polyisocyanates,especially those known as paint polyisocyanates, containing freeisocyanate groups attached to aliphatic, cycloaliphatic, araliphaticand/or aromatic moieties. Preference is given to polyisocyanatescontaining from 2 to 5 isocyanate groups per molecule and havingviscosities of from 100 to 10 000, preferably from 100 to 5000, and inparticular from 1000 to 2000 mPas (at 23° C.). If desired, small amountsof organic solvent, preferably from 1 to 25% by weight based on straightpolyisocyanate, may be added to the polyisocyanates in order to improvethe ease of incorporation of the isocyanate and, where appropriate, tolower the viscosity of the polyisocyanate to a figure within theaforementioned ranges. Examples of suitable solvent additives [lacuna]the polyisocyanates are ethoxyethyl propionate, amyl methyl ketone, andbutyl acetate. Moreover, the polyisocyanates may have beenhydrophilically or hydrophobically modified in a customary and knownmanner.

Examples of suitable polyisocyanates are described, for example, in“Methoden der organischen Chemie”, Houben-Weyl, Volume 14/2, 4thedition, Georg Thieme Verlag, Stuttgart 1963, pages 61 to 70, and by W.Siefken, Liebigs Annalen der Chemie, Volume 562, pages 75 to 136.Suitable examples include polyurethane prepolymers containing isocyanategroups, which may be prepared by reacting polyols with an excess ofpolyisocyanates and which are preferably of low viscosity.

Further examples of suitable polyisocyanates are polyisocyanatescontaining isocyanurate, biuret, allophanate, iminooxadiazinedone,urethane, urea and/or uretdione groups. Polyisocyanates containingurethane groups, for example, are obtained by reacting some of theisocyanate groups with polyols, such as trimethylolpropane and glycerol,for example. It is preferred to use aliphatic or cycloaliphaticpolyisocyanates, especially hexamethylene diisocyanate, dimerized andtrimerized hexamethylene diisocyanate, isophorone diisocyanate,2-isocyanatopropylcyclohexyl isocyanate, dicyclohexylmethane2,4′-diisocyanate, dicylohexylmethane 4,4′-diisocyanate or1,3-bis(isocyanatomethyl)cyclohexane, diisocyanates derived from dimerfatty acids, as sold under the commercial designation DDI 1410 byHenkel, 1,8-diisocyanato-4-isocyanatomethyloctane,1,7-diisocyanato-4-isocyanatomethylheptane or1-isocyanato-2-(3-isocyanatopropyl)cyclohexane, or mixtures of thesepolyisocyanates.

Very particular preference is given to using mixtures of polyisocyanatescontaining uretdione and/or isocyanurate groups and/or allophanategroups and based on hexamethylene diisocyanate, as are formed bycatalytic oligomerization of hexamethylene diisocyanate usingappropriate catalysts. The polyisocyanate constituent may otherwiseconsist of any desired mixtures of the free polyisocyanates exemplifiedabove.

Examples of suitable blocking agents are the blocking agents known fromthe U.S. patent U.S. Pat. No. 4,444,954, such as

i) phenols such as phenol, cresol, xylenol, nitrophenol, chlorophenol,ethylphenol, t-butylphenol, hydroxybenzoic acid, esters of this acid, or2,5-di-tert-butyl-4-hydroxytoluene;

ii) lactams, such as ε-caprolactam, δ-valerolactam, γ-butyrolactam orβ-propiolactam;

iii) active methylenic compounds, such as diethyl malonate, dimethylmalonate, ethyl acetoacetate or methyl acetoacetate, or acetylacetone;

iv) alcohols such as methanol, ethanol, n-propanol, isopropanol,n-butanol, isobutanol, t-butanol, n-amyl alcohol, t-amyl alcohol, laurylalcohol, ethylene glycol monomethyl ether, ethylene glycol monoethylether, ethylene glycol monobutyl ether, diethylene glycol monomethylether, diethylene glycol monoethyl, ether, propylene glycol monomethylether, methoxymethanol, glycolic acid, glycolic esters, lactic acid,lactic esters, methylolurea, methylolmelamine, diacetone alcohol,ethylenechlorohydrin, ethylenebromohydrin, 1,3-dichloro-2-propanol,1,4-cyclohexyldimethanol or acetocyanohydrin;

v) mercaptans such as butyl mercaptan, hexyl mercaptan, t-butylmercaptan, t-dodecyl mercaptan, 2-mercaptobenzothiazol, thiophenol,methylthiophenol or ethylthiophenol;

vi) acid amides such as acetoanilide, acetoanisidinamide, acrylamide,methacrylamide, acetamide, stearamide or benzamide;

vii) imides such as succinimide, phthalimide or maleimide;

viii) amines such as diphenylamine, phenylnaphthylamine, xylidine,N-phenylxylidine, carbazole, aniline, naphthylamine, butylamine,dibutylamine or butylphenylamine;

ix) imidazoles such as imidazole or 2-ethylimidazole;

x) ureas such as urea, thiourea, ethyleneurea, ethylenethiourea or1,3-diphenylurea;

xi) carbamates such as phenyl N-phenylcarbamate or 2-oxazolidone;

xii) imines such as ethyleneimine;

xiii) oximes such as acetone oxime, formaldoxime, acetaldoxime,acetoxime, methyl ethyl ketoxime, diisobutyl ketoxime, diacetylmonoxime, benzophenone oxime or chlorohexanone oximes;

xiv) salts of sulfurous acid such as sodium bisulfite or potassiumbisulfite;

xv) hydroxamic esters such as benzyl methacrylohydroxamate (BMH) orallyl methacrylo-hydroxamate; or

xvi) substituted pyrazoles, ketoximes, imidazoles or triazoles; and also

mixtures of these blocking agents, especially dimethylpyrazole andtriazoles, malonic esters and acetoacetic esters, or dimethylpyrazoleand succinimide.

As crosslinking agents (a7) it is also possible to usetris(alkoxycarbonylamino)triazines of the general formula 5

Examples of suitable tris(alkoxycarbonylamino)triazines (a7) aredescribed in the patents U.S. Pat. No. 4,939,213, U.S. Pat. No.5,084,541 or EP 0 624 577 A1. Use is made in particular of thetris(methoxy-, tris(butoxy- and/ortris(2-ethylhexoxycarbonylamino)triazines.

Of advantage are the methyl butyl mixed esters, the butyl 2-ethylhexylmixed esters, and the butyl esters. These have the advantage over thestraight methyl ester of better solubility in polymer melts, and alsohave less of a tendency to crystallize.

Particularly suitable for use as crosslinking agents (a7) are aminoresins, examples being melamine resins. In this context it is possibleto use any amino resin suitable for transparent topcoat or clearcoatmaterials, or a mixture of such amino resins. Especially suitable arethe customary and known amino resins some of whose methylol and/ormethoxymethyl groups have been defunctionalized by means of carbamate orallophanate groups. Crosslinking agents of this kind are described inthe patents U.S. Pat. No. 4,710,542 and EP 0 245 700 B1 and also in thearticle by B. Singh and coworkers, Carbamylmethylated Melamines, NovelCrosslinkers for the Coatings Industry, in Advanced Organic CoatingsScience and Technology Series, 1991, Volume 13, pages 193 to 207.Furthermore, the amino resins may also be used as binders (a11) in thebase paint (A1).

Further examples of suitable crosslinking agents (a7) arebeta-hydroxyalkylamides such asN,N,N′,N′-tetrakis(2-hydroxyethyl)adipamide orN,N,N′,N′-tetrakis(2-hydroxypropyl)adipamide.

Further examples of suitable crosslinking agents (a7) are siloxanes,especially siloxanes containing at least one trialkoxy- ordialkoxysilane group.

Further examples of suitable crosslinking agents (a7) arepolyanhydrides, especially polysuccinic anhydride.

The coating material of the invention may further comprise organicsolvents (a8) which do not react with isocyanate groups. Particularlysuitable such solvents include esters, ketones, keto esters, glycolethers such as ethylene, propylene or butylene glycol ethers, glycolesters such as ethylene, propylene or butylene glycol esters, or glycolether esters such as ethoxyethyl propionate and isopropbxypropanol. Alsosuitable are aliphatic and aromatic solvents such as dipentene, xyleneor Shellsol®.

The coating material for use in accordance with the invention may bepresent in different forms.

Thus, given an appropriate choice of its above-described constituents,it may be present as a liquid coating material which is substantiallyfree from organic solvents. However, the coating material may comprise asolution or dispersion of the above-described constituents in organicsolvents (a8). It is a further advantage of the coating material of theinvention that in this case solids contents of up to more than 80% byweight, based on the coating material, may be set.

Furthermore, given an appropriate choice of its above-describedconstituents, the coating material may be a powder clearcoat material.For this purpose the constituent (a1) is advantageouslymicroencapsulated. This powder clearcoat material may then be dispersed,if desired, in water to give a powder slurry clearcoat material.

Advantageously, the coating material of the invention is a two-componentor multicomponent system in which at least the constituent (a1) isstored separately from the other constituents and is not added to themuntil shortly before use. In this case, the coating material of theinvention may also be aqueous, the constituent (a1) preferably beingpresent in a component comprising a solvent (a8).

The coating material of the invention is used to produce the clearcoatsand multicoat systems of the invention on primed or unprimed substrates.

Suitable coating substrates in this context are all surfaces which areamenable to combined curing with the use of heat and actinic radiation;examples include metals, plastics, wood, ceramic, stone, textile,leather, glass, glass fibers, glass wool and rock wool, mineral- andresin-bound building materials, such as, plasterboard and cement slabsor roof tiles. Accordingly, the coating material of the invention isalso suitable for applications outside of automotive finishing,especially for the coating of furniture and for industrial coating,including coil coating and container coating. In the context of theindustrial coatings it is suitable for coating virtually all parts forprivate or industrial use, such as radiators, domestic appliances, smallmetal parts, hubcaps or wheel rims.

Using the coating material of the invention it is also possible inparticular to coat primed or unprimed plastics such as, for example,ABS, AMMA, ASA, CA, CAB, EP, UF, CF, MF, MPF, PF, PAN, PA, PE, HDPE,LDPE, LLDPE, UHMWPE, PET, PMMA, PP, PS, SB, PUR, PVC, RF, SAN, PBT, PPE,POM, PUR-RIM, SMC, BMC, PP-EPDM and UP (abbreviations in accordance withDIN 7728T1). The plastics to be coated may of course also be polymerblends, modified plastics or fiber reinforced plastics. The coatingmaterial may also be employed to coat plastics commonly used in vehicleconstruction, especially motor vehicle construction. Unfunctionalizedand/or nonpolar substrate surfaces may be subjected prior to coating ina known manner to a pretreatment, such as with a plasma or by flaming.

In the context of the coating process of the invention it is possiblehere to apply one or more clearcoat(s). Where two or more clearcoats areapplied, coating materials of the invention having different physicalcompositions may be used. In the great majority of cases, however, thedesired profile of properties of the clearcoats and multicoat systems ofthe invention is achieved with one clearcoat.

The clearcoat is applied in a wet film thickness such that after curing,in the finished clearcoats and multicoat systems of the invention, theseal has a dry film thickness of from 10 to 100, preferably from 15 to75, with particular preference from 20 to 55, and in particular from 20to 35 μm.

The application of the coating material of the invention for the purposeof producing the clearcoat film may take place by any customaryapplication method, such as spraying, knifecoating, brushing,flowcoating, dipping or rolling, for example. It is preferred to employspray application methods, such as compressed air spraying, airlessspraying, high-speed rotation, electrostatic spray application (ESTA),for example, alone or in conjunction with hot spray applications such ashot air spraying, for example.

Application may take place at temperatures of max. 70 to 80° C., so thatappropriate application viscosities are attained without any change ordamage to the coating material and its overspray (which may be intendedfor reprocessing) during the short period of thermal stress. Forinstance, hot spraying may be configured in such a way that the coatingmaterial is heated only very briefly in the spray nozzle or shortlybefore the spray nozzle.

The spray booth used for application may, for example, be operated witha circulation system, which may be temperature-controllable, and whichis itself operated with an appropriate absorption medium for theoverspray, an example of such medium being the coating material of theinvention itself.

Application is preferably made under illumination with visible lighthaving a wavelength of more than 550 μm, or in the absence of light.This prevents physical damage or change to the coating material and theoverspray.

Of course, the above-described application methods may also be employedin producing the basecoat of the multicoat systems of the invention, aspart of the coating process of the invention.

In accordance with the invention, following its application theclearcoat film is cured thermally and with actinic radiation.

Curing may take place after a certain rest period. This period may havea duration of from 30 s to 2 h, preferably from 1 min to 1 h, and inparticular from 1 min to 30 min. The rest period is used, for example,for leveling and devolatilization of the clearcoat film or for theevaporation of volatile constituents such as solvents, water or carbondioxide if the coating material has been applied using supercriticalcarbon dioxide as solvent. The rest period may be shortened and/orassisted by the use of elevated temperatures of up to 80° C., providedthis does not entail any damage or alteration to the clearcoat film,such as premature crosslinking, for instance.

In accordance with the invention, curing with actinic radiation takesplace with UV radiation or electron beams. If desired, it may be carriedout or supplemented by actinic radiation from other sources. In the caseof electron beams, it is preferred to operate under an inert gasatmosphere. This may be ensured, for example, by supplying carbondioxide and/or nitrogen directly to the surface of the clearcoat film.

In the case of curing with UV radiation it is also possible to operateunder inert gas in order to prevent the formation of ozone.

Curing with actinic radiation is carried out using the customary andknown radiation sources and optical auxiliary measures. Examples ofsuitable radiation sources are high or low pressure mercury vapor lamps,with or without lead doping in order to open up a radiation window of upto 385 nm, or electron beam sources. The arrangement of these sources isknown in principle and may be adapted to the circumstances of theworkpiece and the process parameters. In the case of workpieces ofcomplex shape, as are envisaged for automobile bodies, the regions notaccessible to direct radiation (shadow regions) such as cavities, foldsand other structural undercuts may be (partially) cured using pointwise,small-area or all-round emitters, in conjunction with an automaticmovement means for the irradiation of cavities or edges.

During the curing of the film(s) present on the substrate and comprisingthe coating material of the invention, the substrate may be at rest ormay be passed in front of the actinic radiation source at an appropriatespeed. If the substrate is moved, a speed of advance in the range fromfrom 1 to 10 m/min, with particular preference from 2 to 8 m/min, and inparticular from 3 to 6 m/min, is found advantageous. In this case the UVlamps have a preferred output of from 100 to 200 W/cm, with particularpreference from 120 to 190 W/cm, and in particular from 140 to 180 W/cm.Irrespective of whether the substrate is moved or is at rest, aradiation dose that proves advantageous is a dose in the range from 500to 5000 mJ/cm², with particular preference from 1000 to 4500 mJ/cm², andin particular from 1500 to 4000 mJ/cm².

The equipment and conditions of [lacuna] these curing methods aredescribed, for example, in R. Holmes, U.V. and E.B. Curing Formulationsfor Printing Inks, Coatings and Paints, SITA Technology, Academic Press,London, United Kingdom 1984.

Curing here may take place in stages, i.e., by multiple exposure tolight with actinic radiation. It may also be carried out alternatingly,i.e., by curing alternately with UV radiation and electron beams.

The thermal curing as well has no special features in terms of itsmethodology but instead takes place in accordance with the customary andknown methods such as heating in a forced air oven or irradiation withIR lamps. As with actinic radiation curing, thermal curing may also becarried out in stages. Thermal curing takes place advantageously at atemperature of from 50 to 100° C., with particular preference from 80 to100° C., and in particular from 90 to 100° C., for a period of from 1min up to 2 h, with particular preference from 2 min up to 1 h, and inparticular from 3 to 30 min. Where the substrates used are able towithstand high thermal loads, thermal crosslinking may also be carriedout at temperatures above 100° C. In this case it is generally advisablenot to exceed temperatures of 180° C., preferably 160° C., and inparticular 140° C.

Thermal curing and curing with actinic radiation are employed together.These methods may be used simultaneously or in alternation. Where thetwo curing methods are used in alternation, it is possible for exampleto begin with thermal curing and to end with curing with actinicradiation. In other cases it may prove advantageous to begin and to endwith actinic radiation curing. The skilled worker is able to determinethe method of curing most advantageous for the case in hand on the basisof his or her general knowledge in the art, possibly with the assistanceof simple preliminary tests. In the great majority of cases it is foundadvantageous first to carry out curing with actinic radiation and thento carry out thermal curing.

The clearcoats of the invention may also be part of the multicoatsystems of the invention.

For this purpose, the coating material of the invention is applied bythe coating process of the invention not to the primed or unprimedsubstrates but instead to at least one color and/or effect basecoat filmwhich is situated thereon and comprises a pigmented coating materialcurable thermally and also, where appropriate, with actinic radiation.

In accordance with the invention it is of advantage to apply the coatingmaterials of the invention by the wet-on-wet technique to the dried orflashed-off, but not fully cured, basecoat film, after which theresultant clearcoat film and the basecoat film are cured togetherthermally and with actinic radiation.

Suitable coating materials for producing the basecoat film include thecustomary and known basecoat materials, especially aqueous basecoatmaterials.

Examples of suitable aqueous basecoat materials are known from thepatents EP 0 089 497 A1, EP 0 256 540 A1, EP 0 260 447 A1, EP 0 297 576A1, WO 96/12747, EP 0 523 610 A1, EP 0 228 003 A1, EP 0 397 806 A1, EP 0574 417 A1, EP 0 531 510 A1, EP 0 581 211 A1, EP 0 708 788 A1, EP 0 593454 A1, DE 43 28 092 A1, EP 0 299 148 A1, EP 0 394 737 A1, EP 0 590 484A1, EP 0 234 362 A1, EP 0 234 361 A1, EP 0 543 817 A1, WO 95/14721, EP 0521 928 A1, EP 0 522 420 A1, EP 0 522 419 A1, EP 0 649 865 A1, EP 0 536712 A1, EP 0 596 460 A1, EP 0 596 461 A1, EP 0 584 818 A1, EP 0 669 356A1, EP 0 634 431 A1, EP 0 678 536 A1, EP 0 354 261 A1, EP 0 424 705 A1,WO 97/49745, WO 97/49747, EP 0 401 565 A1, EP 0 730 613 B1 or WO95/14721.

The clearcoats and multicoat systems of the invention exhibit excellentscratch resistance, intercoat adhesion, weathering stability andchemical stability, an outstanding profile of optical properties, andextremely high reflow.

EXAMPLE 1 The Production of a Multicoat System of the Invention

A commercial primer-surfacer from BASF Coatings AG was applied first ofall, using a gravity-feed gun, to steel panels coated cathodically witha commercially customary electrodeposition coating material (electrocoathaving a film thickness of 18-22 μm), and baked. This gave aprimer-surfacer coat with a film thickness of from 35 to 40 μm.Thereafter, for the purpose of better assessing the optical propertiesof the clearcoat film of the invention, the primer-surfacer wasovercoated with a black aqueous basecoat material from BASF Coatings AG,which was dried initially at 80° C. for 10 minutes. This aqueousbasecoat material was applied in a wet film thickness such thatfollowing its complete curing the resulting dry film thickness was from13.5 to 15 μm.

Applied wet-on-wet to the basecoat film was a coating material curablethermally and with actinic radiation, in a wet film thickness such thatfull curing of the clearcoat film resulted in a film thickness of 35 μm.The coating material consisted of 136 parts by weight of an aliphaticurethane acrylate based on the isocyanurate of hexamethylenediisocyanate, which contains 12.5% by weight of isocyanate groups andhad an average acrylate group functionality of 3.5, 47.9 parts by weightof 2,4-diethyl-1,5-octanediol, 13.6 parts by weight of a commercialphotoinitiator (Irgacure® 184 from CIBA AG), 1.36 parts by weight of acommercially customary silicone-based leveling agent, 1.36 parts byweight of a commercial defoamer (BYK® 020 from Byk) and 20 parts byweight of butyl acetate.

Following a rest period of 6 min, the resultant basecoat film andclearcoat film were cured at 50° C. with UV radiation (3000 mJ/cm²) andthen baked at 160° C. for 45 min.

The adhesion of the multicoat system of the invention was determinedfollowing 24 hours of storage at room temperature in accordance with thecross-cut test to DIN 53151 (2 mm) [ratings 0 to 5]. There was nodelamination: rating GT0.

The scratch resistance of the multicoat system on the test panels wasassessed following two weeks of storage at room temperature by means ofthe BASF brush test described in FIG. 2 on page 28 of the article by P.Betz and A. Bartelt, Progress in Organic Coatings, 22 (1993), pages27-37, albeit with modification in respect of the weight used (2000 ginstead of the 280 g specified therein), assessment taking place asfollows: In the test, the film surface was damaged using a mesh fabricloaded with a mass. The mesh fabric and the film surface were wettedcopiously with a laundry detergent solution. The test panel was movedback and forward under the mesh fabric in reciprocal movements by meansof a motor drive.

The test element was an eraser (4.5×2.0 cm, broad side perpendicular tothe direction of scratching) covered with nylon mesh fabric (no. 11, 31μm mesh size, Tg 50° C.). The applied weight was 2000 g.

Prior to each test the mesh fabric was replaced, with the runningdirection of the fabric meshes parallel to the direction of scratching.Using a pipette, approximately 1 ml of a freshly stirred 0.25% strengthPersil solution was applied in front of the eraser. The rotary speed ofthe motor was adjusted so that 80 double strokes were performed within aperiod of 80 s. After the test, the remaining washing liquid was rinsedoff with cold tap water and the test panel was blown dry usingcompressed air. The gloss for DIN 67530 was measured before and afterdamage (measurement direction perpendicular to the direction ofscratching), and gave the following results:

Initial gloss 86 Gloss after exposure 63 Gloss after storage 83 at 60°C. for 2 hours

The results evidence the good scratch resistance and extremely highreflow of the multicoat system of the invention.

In terms of its chemical resistance, the multicoat system of theinvention corresponded to the multicoat systems produced with the aid ofcustomary and known two-component (2k) clearcoat materials.

What is claimed is:
 1. A coating material curable thermally and withactinic radiation, comprising (a1) at least one constituent comprising(a11) at least two functional groups which serve for crosslinking withactinic radiation, and (a12) at least one functional group which is ableto undergo thermal crosslinking reactions with the hydroxyl and/or thiolgroups (a21) in the constituent (a2) and is at least one of

and (a2) at least one branched, cyclic and/or acyclic C₉-C₁₆functionalized alkane comprising at least two functional groups (a21)selected from the group consisting of hydroxyl groups, thiol groups, andmixtures thereof.
 2. The coating material of claim 1, further comprisingat least one member selected from (a3) at least one photoinitiator, (a4)at least one thermal crosslinking initiator, (a5) at least one reactivediluent curable thermally and/or with actinic radiation, (a6) at leastone coatings additive, (a7) at least one thermally curable constituent,(a8) at least one organic solvent, and mixtures thereof.
 3. The coatingmaterial of claim 1, wherein functional groups (a11) comprise at leastone group selected from olefinically unsaturated groups, epoxide groups,and mixtures thereof, and functional groups (a12) comprise isocyanategroups.
 4. The coating material of claim 1, wherein constituent (a1)comprises at least one member selected from a urethane (meth)acrylate, apolyester (meth)acrylate, or mixtures thereof.
 5. The coating materialof claim 1, wherein functionalized alkane (a2) is liquid at roomtemperature.
 6. The coating material of claim 1, wherein functionalizedalkane (a2) has a boiling point of over 200° C.
 7. The coating materialof claim 1, wherein functionalized alkane (a2) is acyclic.
 8. Thecoating material of claim 1, wherein functionalized alkane (a2)comprises primary and/or secondary hydroxyl and/or thiol groups.
 9. Thecoating material of claim 1, wherein functionalized alkane (a2)comprises primary and secondary hydroxyl and/or thiol groups.
 10. Thecoating material of claim 1, wherein functionalized alkane (a2) is apolyol (a2).
 11. The coating material of claim 10, characterized in thatthe polyols (a2) are diols and/or triols (a2).
 12. The coating materialof claim 11, characterized in that the polyols (a2) are positionallyisomeric dialkyloctanediols.
 13. The coating material of claim 12,characterized in that the polyols (a2) are positionally isomericdiethyloctanediols.
 14. The coating material of claim 12, characterizedin that the polyol (a2) comprises 2,4-diethyl-1,5-octanediol.
 15. Aprocess of coating a substrate comprising applying to a substrate thecoating material of claim
 1. 16. The process of claim 15 wherein theapplied coating material is at least one coating selected from abasecoat or a clearcoat.
 17. The process of claim 15 wherein thesubstrate is an automotive part, an article or component of furniture, acoil, or a container.